In the past, physical entrapment typically was used to immobilize detection matrices on a molded polymer substrate in analytical systems designed for the diagnostic testing of liquid samples, e.g., biological samples from a patient or subject. In such systems, the molded substrate physically holds the detection matrix in place. Analytical testing, however, is not feasible in such systems, especially with dense or colored liquids, because the detection matrix has a tendency to slide or move away from its original position on the substrate. Under these circumstances, the liquid sample can infiltrate between the substrate and the detection matrix and potentially interfere with optical measurements. Further, in optical measurements, the matrix can move out of the focal point of the interrogating light source, causing inaccurate or even false negative readings.